I just noticed the same problem. It's definitely a bug.

As a workaround I created overloaded extension method.

        public static IEnumerable<IContent> GetAncestors(this IContentLoader loader, ContentReference contentReference, ILanguageSelector selector)
        {
            // NOTE IContentLoader.GetAncestors returns only content in master language! 
            // Therefore we must retrieve the correct language branch manually
            var ancestors = loader.GetAncestors(contentReference);
            return ancestors.Select(ancestor => loader.Get<IContent>(ancestor.ContentLink, selector))
                            .Where(content => content != null);
        }

    

 

 

There is some reasoning about the decision to let GetAncestors return the master language, see this thread.

But it could be clearer from the documentation that the master language is selected, I'll try to make sure it is mentioned in the API docs.

public static class GetAncestorsExtension

{
        public static IEnumerable<IContent> GetAncestors(this IContentLoader loader, ContentReference contentReference, ILanguageSelector selector)
        {
            // NOTE IContentLoader.GetAncestors returns only content in master language!
            // Therefore we must retrieve the correct language branch manually
            var ancestors = loader.GetAncestors(contentReference);
            return ancestors.Select(ancestor => loader.Get<IContent>(ancestor.ContentLink, selector.Language))
                            .Where(content => content != null);
        }

}

Had to specify selector.Language to make this work.
Thanks

<p>I agree with reasoning that GetAncestors() should return all&nbsp;ancestor items independent of language versions. But why don't return a collection of content links? It is usual when you only need links anyway and if you want to get content items - you manually&nbsp;load them in the desired language. Moreover opposite GetDescendants() method works exactly like that. This change&nbsp;will remove&nbsp;API inconsistency and the need to document edge cases.</p>